Muffler with spiral partition



Dec. 4, 1962 W. C. DEHL MUFFLER WITH SPIRAL PARTITION Filed April 2l, 1960 BWMWZM@ United States Patent Oiiice 3,056,755 Patented Dec. 4, 1962 3,066,755 MUFFLER WITH SPIRAL PARTITION William Carl Diehl, 7604 Park Ave., North Bergen, NJ. Filed Apr. 21, 1960, Ser. No. 23,707 13 Claims. (Cl. 181-66) This invention relates to means for treating exhaust gases from an internal combustion engine and more especially to means for controlling the pressure and temperature conditions of the exhaust gases as they are discharged from the exhaust manifold of the internal combustion engine. The invention particularly relates to a muffler 4for the exhaust conduit from an internal combustion engine.

Heretofore devices of many kinds have been proposed for treating the exhaust gases from an internal combustion engine which are explosively discharged therefrom, ordinarily from an exhaust manifold connected to a plurality of cylinders of the engine. Mulers constructed with baffles or with partitions, including spiral partitions, or other devices have been proposed for receiving the exhaust gases discharged from the engine and changing the pressure-velocity conditions thereof so that the gases may be discharged from the muler without marked explosive change in the pressure and velocity thereof at the outlet of the muiiier creating undesirable noise. Such devices have been more or less effective to reduce noise but, depending on the size `of the engine and the quantity of exhaust gas discharged therefrom, these prior art devices have been of large dimensions and have required a large amount of material, their structures also being complicated, resulting in excessive Weight, space requirements and cost. The prior art constructions also have developed substantial back pressures against which the exhaust gases discharged by the engine must flow, `requiring expenditure of additional power in the engine. Moreover, the problem of eliminating or reducing the smoke content in the exhaust gases has not been satisfactorily solved.

It is an object of the invention to provide means for treating exhaust gases from an internal combustion engine to provide improved muling of the noise of their discharge with limitation of the back pressure developed.

it is another object of the invention to provide a muifler of simple construction for the exhaust conduit from an internal combustion engine in which the pressurevelocity conditions of the gases are controlled so that withinv relatively small dimensions of the muffler the desired reduction of noise is secured.

It is a further object of the invention to provide a mufller for the exhaust conduit of an internal combustion engine in lwhich the energy of the gases explosively discharged from the internal combustion engine is absorbed in the muler without the development of substantial back pressures.

It is -an additional object of the invention to provide a chamber for treating the exhaust gases from an internal combustion engine in which the heat conditions are controlled so as to be favorable to improving the completeness of the combustion of combustible materials contained in the exhaust gases.

It is a feature of the invention that, within a casing having an inlet opening connected to the exhaust manifold of an internal combustion engine, a spiral partition is provided between the wraps of which is formed a relatively narrow spiral passage the inlet portion of which disposed at the larger diameter of the spiral communicates with the inlet opening of the casing, the gases from the engine flowing through the inlet opening into the inlet portion of the spiral passage and then inwardly along the spiral passage toward an end of this passage defined by the portion of the spiral partition disposed at la smaller diameter of the spiral. This inner end of the passage is connected to a central passage extending generally parallel to the axis `of the spiral. The relatively restricted area of the spiral passage is secured by relatively close spacing of the adjacent wraps of the spiral. As a result a high speed of the gases ilowing through the spiral passage toward the central passage is attained with concomitant reduction `of the pressure of the gases and discharge thereof into the atmosphere without great explosive action. A continuous forward flow of gases through the spiral passage is secured which avoids the back pressure reactions which are developed in effecting movement of the gases sharply about battles. Moreover, the ilow of gases through the spiral at high speed develops a substantial turbulence therein which is effective for transferring heat from the gases to the spiral partitions which define the spiral passage as well as for effecting thorough mixture of the combustible constituents `of the gases for purposes :about to be described.

lt is another feature of the invention that the inner portion of the spiral passage is connected to the central passage through a gas directing opening which directs the gases to flow into the central passage from the adjacent portion of the spiral passage. This gas directing opening may be an elongated opening extending generally parallel to the axis of the spiral and may be of restricted width transverse to this extent. Preferably a vane or wall is disposed along the gas directing opening in opposed relation to and at the opposite side of this opening from a part of the spiral partition which deiines the central passage. The gases thereby are directed to flow generally along the wall `of the central passage and about the axis of the spiral. This rotational movement of the gases develops a suction at the opening which is carried back through the spiral passage to reduce the pressure therein and to reduce the back pressure on the engine. Deflectors also are provided which direct the gases as they pass through the elongated opening into the central passage to flow toward the discharge opening of the muffler. 4

It is a further feature of the invention that the structure of the muffler provides for transfer of heat through the spiral partition deiining the spiral passage successively to the gases in adjacent portions of the passage inwardly of and at the opposite side of the partition and then to the gases within the central passage for effecting more complete combustion of the combustible materials contained in the exhaust gases. This combustion may be effected with the aid of auxiliary air introduced through an auxiliary opening, or with the aid of an auxiliary heating device or a hot gas producing unit connected to the auxiliary opening for supplying auxiliary gases of high temperature. Moreover, the turbulence developed in the gases flowing at high speed in the spiral passage not only brings about more thorough mixture of the hot and cooler portions of the gases but improves the heat transfer to the partition to maintain its temperature as regenerative means.

Other objects and features of the invention will be understood from the description of the drawings to follow in which:

FIG. 1 shows the muler of the invention connected to the air intake of the carburetor of an internal combustion engine;

FIG. 2 is a section to enlarged scale taken on line 2 2 of FIG. l;

FIG. 3 is a section on line 3-3 of FIG. 2;

FIG. 4 shows in perspective to enlarged scale a fragmentary and sectional view of a modified form of the spiral partition;

fn Ll) FIG. shows to enlarged scale a modification of a part of the device.

ln FIGS. l and 2 the muffler 10 is constructed with a casing 11 which may be of metal and of tubular or preferably cylindrical form provided with an inlet conduit 13 connecting to an inlet opening 1S in the peripheral Wall of the casing and provided with an outlet conduit 17 connected to an outlet opening 19 of generally circular cross section disposed coaxially with the axis of the cylindrical casing 11 in the end wall 23 of the chamber 21 which is formed within the casing 11, this chamber being closed by end walls 23, 2e' transverse to the axis of the cylinder. These end walls also may be of metal.

Within the chamber 21 is disposed a spiral partition 27 which may be of metal and formed substantially upon the axis of the cylinder 11 and having its end 29 at the larger diameter thereof connected to the casing 11 adjacent the inlet opening and in such relation to the inlet pipe 13 that the gases flowing in the direction of the arrow 14 through the conduit 13 into the casing pass into the outer portion of the spiral passage 31 formed between the spiral partition Z7 and the casing 11 and then flow in the direction of the arrow 32 between the successive inwardly disposed wraps yof the partition 27. rl`he inner portion of the partition 27 is disposed adjacent a tubular 0r preferably cylindrical wall 33 concentric with the axis of the casing 11 and defining a central passage 35 extending along the axis between the end walls 2,3, 25. IIn the particular embodiment being described, as shown in FIG. 2, the inner portion of the partition 27 is connected to the cylindrical Wall 33, the end 37 of the innermost spiral wrap of the partition 27 forming with the cylindrical wall 33 adjacent the end 37 of the partition a space 39 which will be referred to as a dead space for the resaon that the end of this space is closed off by the connection of the end 37 Iof the partition to the wall 33. The function of this dead space will be further described hereinafter.

`It will be noted that the end portion 37 of the partition is disposed in generally tangential relation to the circle of the central space defining wall 33. in the direction forwardly of the portion 37 the wall 33 is provided with a gas directing opening 41 therethrough which establishes communication between the part 43 of the spiral passage disposed between the end portion 37 of the spiral partition and the next outwardly disposed wrap of this partition. The opening 41 may be formed by a vane 45 extending parallel t-o the axis of the cylinder and of the spiral and may be disposed in opposed relatively closely spaced relation to a part 47 of the cylindrical wall 33. This part 47 of the wall 33 may be bent slightly outwardly so as to be parallel to the vane 45, this part and the vane extending along the axis substantially between the end walls 23, 25 of the chamber and forming an elongated gas direction opening for conveying gas from the portion 43 of the spiral passage into the central passage 35 through which and through the outlet conduit 17 the gases flow in the direction of the arrow 18, FIG. 3.

In accordance with the invention a plurality of wraps of the spiral partition 27 are provided so that the spacing of adjacent wraps may be restricted to form a relatively narrow spiral passage from the inlet opening 15 to the gas directing opening 41. In a muffler designed for use with a conventional automobile engine, for example an engine for a commercial truck, the diameter of the casing 11 may be about 8 inches and the length thereof parallel to the axis may be about 8 inches. In such a gas engine plant the diameter of the inlet pipe 13 carrying the exhaust from the engine may be, for example, 21/2 inches and the diameter of the outlet pipe 17 also may be about 21/2 inches. Allowing for a thickness of the partition 27 of about 1A: inch when constructed as shown in FIG. 4 and further to be described, the spacing of the wraps of the spiral 27 in FIGS. 2 and 3 would be approximately 1/2 inch. lf the number of wraps is increased, for example 4l. to 6 wraps, the spacing between the wraps would be reduced to about li inch. Having regard to the volume of gases discharged by a gasoline engine of this character, a high velocity of the gases moving through the spiral passage toward the central passage will be developed with substantial turbulence in these gases for effecting mixture thereof and of Ithe combustible materials which may be carried thereby, This turbulence also, as above mentioned, is conducive to a high heat transfer from the gases to the spiral partition 27 along its length, so that this partition thus retaining heat as a regenerative element may assist in effecting combustion of unburned combustible gases and products within the casing 11. To this end in some cases it may be necessary to supply additional air for the combustion and this may be effected through the auxiliary opening 5l, as shown in FIG. 3. The device of the invention, therefore, in addition to its muflling action to be `described further, is capable of effecting more thorough combustion of combustible gas and carbon carried in the exhaust gases so that they may be discharged with much reduced smoke through the discharge conduit It will be understood that the gases passing inwardly through the spiral passage 31 and reaching the portion d3 thereof will tend to continue spirally through the portion 53 of the spiral passage about the axis of the spiral, this portion gradually contracting in width and leading into the dead space 39. A part of the gases will thus spirally flow to the dead space but another part thereof will flow through the opening 41 into the central space 35 as above described. The portion which flows into the dead space 39 cannot continue to flow spirally. The wall 33 which denes the central space 35, however, is provided with perforations 55 through which the gases as they become slightly compressed in the dead space may pass into the central space 35. The number of perforations 55 provided in the wall 33 defining the central space may be made greater or less according to the amount of gases which it is desired to be caused to flow toward the dead space and thence through the wall 33 into the central passage as compared with the amount which it is desired to pass through the elongated opening 41 into the central space 35. The dead space 39 acts in the manner of a cushion which the spirally flowing gases in the portion 53 of the passage meet, the energy of their flow becoming absorbed to a substantial extent in this cushion with the development of an increased pressure which is effective to force the gas through the perforations 55 into the central space 35. The cushioning of this part of the gas flow is effective to reduce the noise of discharge, that is, to increase the mufller action. This muiller action, however, is secured to a great extent by the provision of the narrow spiral passage to secure the change of the pressure as the gases are exhausted concomitantly with increase in the velocity of flow.

The portion of the gases which flow through the opening 41 are effective to produce a rotational movement of the gases within the space 35. This is accomplished by virtue of the disposition of the vane 4S and wall 47 which direct the gases tangentially toward the cylindrical wall 33, thereby to Vdevelop a rotational movement about the axis of the cylindrical wall 33. This rotational movement of the tangentially directed gases flowing through the elongated opening 41 is conducive to developing suction on the portion 43 of the spiral passage, thereby to develop a reduction of the pressure extending backwardly through the spiral passage to the opening 15. This may be effective, together with the reduction of the pressure in the spiral passage by virtue of the high velocity of the gases, to decrease the pressure on the exhaust manifold and thereby to relieve the back pressure on the engine.

In order to assist in directing the liow of the gases passing through the elongated gas directing opening 41, in accordance with another feature of the invention a plurality of deilectors 61 are disposed with respect to the vane 45 and the Wall 47 so that the gases flowing through the opening 41 are directed along the axis toward the discharge opening 19 of the muffler. The deflectors 61, as shown in FIGS. 2 and 3, may be disposed at an angle both Ito the lengthwise extent of the opening 41 parallel to the axis as well as in inclined relation to the parallel surfaces of the vane y45 and the wall 47, so that the gases may tend to move spirally along the inner surface of the cylindrical wall 33 as Well as toward the discharge opening 19.

In the embodiment shown in FIGS. 2 and 3, these deflectors I61 are disposed with a portion thereof within the space between the vane 45 and the Wall 47. Within the scope of the invention, however, these deflectors may be disposed as shown in FIG. 5 substantially with their full extent within the space 35, the lower ends of the deflectors in FIG. 5 being disposed substantially at the upper edge 46 of the vane 45.

The deflectors 61 may be made of metal and may be secured to the vane 45 and to the wall portion 47 by suitable means, for example, by welding 91. The spiral partition also may be made of metal, the outer end Z being welded at 93 to the inner side of the casing 11 and the inner end 37 thereof adjacent the vane 45 being welded at 95V to the cylindrical wall 33. The ends walls 23, 25 of the muffler also may be welded by welds 97 at their peripheries to the casing 11 and the outlet and inlet conduits 17, 13 and the connector 52 defining the auxiliary opening 51 may be welded by welds 99 to lthe casing and to the end walls.

As shown in FIGS. 2 and 3 the spiral partition 27 may be provided along its full extent between the outer end 29 and the portion thereof adjacent the dead space 39 with perforations 63 through which the gases may pass from one portion of the spiral passage to the adjacent portion disposed inwardly thereof. This provision of the perforations 63 provides for relief of the pressure which may develop in the spiral passage or in a portion thereof by ow of the gases through the perforations 63, so that the pressure of the gases ordinarily explosively discharged from the engine may gradually be reduced concomitantly with increase in the speed of flow of these gases. Thus, as they enter and flow through the central passage 35 and are discharged through the discharge opening 19 they meet the atmosphere at a pressure close to the atmospheric pressure and, therefore, are not explosively discharged into the atmosphere. The result is that the device of the invention provides very effectively for mufliing which is necessary and desirable for gases discharged from internal combustion engines.

As shown in FIG. 4 the spiral partition 27, if desired, may comprise two parallel walls 65, 67 each of which may be provided with perforations 69. The walls 65, 67 are supported in the casing by suitable means in spaced relation to each other and a filler 71 of a refractory material, for example expanded vermiculite, may be disposed within the space between the walls 65, 67. This refractory material preferably is of such character as to provide interstices between the particles thereof which afford a relatively large area of ow through the filler material 71 for the gases which may pass through the perforations 69 in the walls 65, 67. It will be appreciated that the partition 27, when thus constructed to include a filler material such as vermiculite, will provide a heat accumulating mass which will increase the regenerative action of the partition referred to above. Moreover, as the gases flow through the partition and through the interstices of the filler, the sound deadening action is increased; The thickness of the walls 65, 67 may be of the degree of 3/16 to s of an inch depending on the construction of the mufier. These Walls may be welded at their ends to the end walls 23, of the muffler and, if desired, intermediate spacers 73 may be provided to maintain the separation adjacent the mid portions of these walls. Likewise in the construction of FIGS. 2 and 3 d between the several wraps of the spiral 27 supporting studs 75 may be disposed to maintain the spacing of these wraps adjacent the mid portion thereof between the end walls 23, 25.

In order to improve the combustion of unburned gases and smoke carried in the exhaust gases within the chamber 21 before discharge thereof at the opening 19, a burner or torch which, for example, may be supplied with propane gas or similar fuel, may be disposed in the auxiliary inlet 51 to ensure that combustible materials reaching the central space are consumed therein. This torch also, if desired, may be disposed at some other part of the device, for example at a selected place in the spiral passage 3'1.

As shown in FIG. l the auxiliary opening 51 defined by the connector 52 may be connected by pipe or conduit- 77 to the air intake 79 of an air filter 81 positioned above the carburetor 83 disposed immediately above the intake 35 of the intake manifold 87 of a 4-cylinder internal combustion engine. To take care of burning the unburned fuel and combustibles carried in the exhaust, especially in the period immediately after starting the engine, and to prevent discharge as smoke into the atmosphere until the engine is heated, the exhaust gases may be carried through the pipe 77 from the opening 51 of the muler casing 11 into the air intake 79 and the air filter 31 to be mixed with the fuel and air delivered to the carburetor, so that these unburned products will be redelivered to the engine for combustion therein. When, however, the muier and its inner structure including the spiral partition therein become highly heated in the manner above described, these unburned products carried by the exhaust from the engine may be burned in the muier and discharged therefrom substantially without smoke. The connection to the air intake 79 then may be shut off by closing the butterfly valve 89 in pipe 77.

Within the scope of the invention the form and dimensions of the chamber 11 may be modified and the number of spiral wraps disposed within the casing, the thickness of the spiral partition and the width of the spiral passage between the wraps may be varied to suit different conditions in connection with different internal combustion engines, while maintaining the features of the invention which relate more particularly to the securing of high speed of flow of the gases through the spiral passage and into the central space, the injection of gases into the central space through the tangentially disposed gas directing opening, and the provision of the dead space for increasing the muliling action. The number, spacing and size of perforations in the positions which have been described along the length of the spiral partition may be varied, these perforations preferably being omitted in the inner end portion of the spiral partition. The deflectors 61 may be set at different angles and, when used in connection with a muffler connected as in FIG. l, at least some of these deflectors may be set at an angle to direct so-me of the gases toward the opening 51. All such variations are intended to come within the scope of the appended claims.

I claim:

l. An exhaust gas treating device comprising a casing defined by a tubular wall and having an inlet opening in said wall, a spiral partition Within said casing defining between the wraps thereof a continuous spiral gas flow passage, said partition having the end thereof at the larger diameter of the spiral connected to the casing Wall adjacent said inlet opening and defining with said casing wall an inlet portion of said spiral passage, a central tubular discharge member defining a central passage disposed adjacent and extending generally parallel to the axis of the spiral of said partition, said casing having a discharge opening communicating with said central passage for discharge of gases from said central passage through said discharge opening, said central tubular member having a gas directing opening in the wall thereof extending generally parallel to said axis of the spiral, the inner end portion of said spiral partition being connected to the wall of said tubular member adjacent and upstream with respect to said gas directing opening, whereby gases travelling from said inlet opening through said spiral passage may pass through said gas directing opening into said central passage defined by said tubular member, said tubular member and the adjacent outwardly disposed portion of said spiral partition providing av continuation of said spiral passage closed at the end thereof and forming a cushion space for the gases flowing thereinto.

2. A device as defined in claim 1 which comprises a vane connected to said inner portion of said spiral partition and extending into said central passage and along said gas directing opening generally parallel to the axis of the spiral for directing gases from said portion of the spiral passage adjacent said inner portion of said partition to flow through said gas directing opening into said central passage in a predetermined relation to said tubular member.

3. A device as defined in claim 2 in which the area of said gas directing opening relative to the area of the portion of said spiral passage adjacent said tubular member is such as to provide for directing a part of the gases to continue along said continuation of the spiral passage and a part of said gases to fiow through said gas directing opening into said central passage.

4. A device as dened in claim 2 in which said vane is disposed so as to direct the flow of gases through said gas directing opening against the inner side of said wall of said tubular member so as to develop rotational movement of said gases in said central passage about the axis of said spiral.

5. A device as dened in claim 1 in which said wall of said tubular member in the portion thereof disposed between said central passage and said continuation of said spiral passavo isV provided with a plurality of 'perforations for ow therethrough of gases from saidfushion space into said central passage.

6. A device as dened in claim 1 in which said spiral partition comprises a plurality of spiral walls disposed in parallel relation to each other along the spiral and defining therebetween a Vspiral space, and discrete heat resisting material disposed in said spiral space between said walls.

7. A device as deined in claim 6 in which said parallel spiral walls are provided with perforations therethrough to provide for liow of gases through said perforations and through said spiral space between adjacent portions of said spiral passage separated by said spiral partition.

8. A device as defined in claim 1 in which said casing wall is cylindrical and generally coaxial with the axis of said spiral, said tubular member defining said central passage with a generally circular cross section substantially coaxial with the axis of said spiral.

9. A device as defined in claim 1 in which said casing is provided with an auxiliary opening disposed along the axis of the spiral at the opposite side of said casing from said gas discharge opening from said central passage, said auxiliary opening communicating with said central passage for iiow of gas through said auxiliary opening.

10. A device as deiined in claim 9 in which said tubular member is adapted to contain means for effecting cornbustion in said central passage of unburned combustible constituents of the exhaust gases delivered into said casing through said inlet opening.

l1. An exhaust gas treating device comprising a casing defined by a tubular wall having an inlet opening in said wall, a spiral partition within said casing defining between the wraps thereof a continuous spiral gas iiow passage, said partition having the end thereof at the larger diameter of the spiral connected to the casing wall adjacent said opening and defining with said casing wall an inlet portion of said spiral passage, a central tubular discharge member defining a central passage disposed adjacent and extending generally parallel to the axis of the spiral of said partition, said casing having a discharge opening communicating with said central passage for discharge of gases from said central discharge through said discharge opening, said tubular member having a gas directing opening in the wall thereof extending generally parallel to said axis of the spiral, the inner end portion of said spiral partition being connected to the wall of said tubular member adjacent and upstream with respect to said gas directing opening, whereby gases travelling from said inlet openin through said spiral passage may pass through said gas directing opening into said central passage defined by said tubular member, and a plurality of defiectors disposed in spaced relation to each other along said gas directing opening into said central passage for deiiecting the gases entering said central passage to flow along said central passage toward said discharge opening of said casing.

12. An exhaust gas treating device comprising a casing `defined by a tubular wall and having an inlet opening in said wall, a spiral partition within said casing defining between the wraps thereof of a continuous spiral gas flow passage, said partition having the end thereof at the larger ydiameter of the spiral connected to `the casing wall adjacent said inlet opening and defining with said casing wall an inlet portion of said spiral passage, a central tubular discharge member defining a central passage disposed adjacent and extending generally parallel to the axis of the spiral of said partition, said casing having a discharge opening communicating with said central passage for discharge of gases from said central passage through said discharge opening, said central tubular member having a gas directing opening in the wall thereof extending generally parallel to said axis of the spiral, the inner end portion of said spiral partition being connected to the wall of said tubular member adjacent and upstream with respect to said gas directing opening, whereby gases traveling from said inlet opening through said spiral passage may pass through said gas directing opening into said central passage defined by said tubular member.

13. A device as defined in claim 12 in which said gas directing opening is denfied by a part of said tubular member wall and by a vane connected to said inner end portion of said spiral partition and extending along said opening in opposed relation to said part of said tubular member wall, said part and said vane being disposed in relation to said inner portion of said partition so as to direct gases to flow through said gas directing opening into said central passage from the portion of said spiral passage disposed at the outer side of said tubular member.

References Cited in the file of this patent UNITED STATES PATENTS 1,680,537 Grooms Aug. 14, 1928 1,756,897 Bilsky Apr. 29, 1930 2,139,736 Durham Dec. 13, 1938 2,325,543 Redinger July 27, 1943 2,642,895 Bertin et al. June 23, 1953 2,908,344 Maruo Oct. 13, 1959 FOREIGN PATENTS 557,140 Germany Aug. 19, 1932 751,940 Great Britain July 4, 1956 

